The present invention relates to a concept for measuring a fiber direction of a carbon fiber material, like for example for quality testing and/or further processing and for a manufacturing of an object in a carbon fiber composite construction.
In modern lightweight construction, more and more carbon fibers are used for increasing the strength of so-called carbon fiber composite materials. In particular with safety-critical members made of these composite materials, like e.g. in aircraft construction, automobile construction or the like the correct position and the correct course, i.e. the direction of the carbon fibers are of decisive importance for the mechanical strength and load capacity of the complete member. At any point or at any relevant points of the work piece, it is a need to measure the fiber course or the angle in which the carbon fibers are positioned with a certain accuracy. Conventionally, in manufacturing several layers of carbon fiber fabrics are stacked, one after the other on top of each other and each soaked with special plastics and hardened or cured. Each of these layers has to be qualified with respect to the fiber course. As the carbon fiber layers are non-transparent for visible light, testing the fiber direction has to be executed individually for each layer each after depositing the layer.
Until now, the fiber direction has been measured or controlled in different ways, i.e. a) visually by the production staff, b) by depositing marks by the production staff, detecting the marks by means of a camera system and further processing the camera images by a corresponding software, and c) by recording the carbon fibers using a camera system whose pixel resolution has to be so high, however, that the individual carbon fibers are visually resolved so that from the image data by means of a special software the direction of the carbon fibers may be determined in any place of the image.
Solutions a) and b) need the help of the production staff and are thus difficult to reproduce and error prone due to the known subjective effects. Apart from that, the solutions are time-consuming and thus expensive. A completely automated testing is not possible. Solution c) needs a comparatively high pixel resolution of the used camera. Apart from higher costs for a camera with a high resolution, with higher pixel numbers more image data result, which leads to a higher image transmission speed and a higher computing power for image evaluation at the same bitrate. A higher data rate and high computing power again lead to higher costs. On the other hand, this means that with a certain expenditure the testing speed is limited. Finally, this means that for testing a certain area of a carbon fiber composite member, acceptable costs determine the testing speed. A further disadvantage is the fact that the fiber direction has to be calculated by software from the image data. The accuracy and reliability of the results thus substantially depend on the quality of the software. In particular with fabric soaked by plastics, the detection of the fiber direction is substantially more inaccurate and less reliable than with a non-soaked so-called “textile” fabric.
Thus, a concept for measuring the fiber direction of a carbon fiber material would be desired or a concept for manufacturing an object in a carbon fiber composite construction which overcomes above mentioned disadvantages or enables a more cost-effective manufacturing with the same quality or accuracy.